My 2010 RAM 1500 has 20" inch wheels and has a 17" spare tire. Window sticker said it had a limited use full size spare tire.

I need someone to confirm this since I have the 3.92 LSD differential. It would seem that the differential would lock up when the tires have 3" of difference when used on the rear./

I would not call a 17" tire full size. Narower is OK but not smaller.


HKS

 

Welcome to the site. The tire may be 'fatter' but with a smaller wheel diameter that the low profile of the 20". I will move this thread to the fourth generation Ram section as they can help you,
FF

 

It is a 235 85 17 which is about .5" shorter than a stock 20.

I was always taught, do not run a smaller spare on a drive wheel. I have mine on the front right now, but I am not engauging the 4x4 in the summer

The spare also has an S speed rating, so highway speeds will not hurt it.

 

CarGuyOhio,

Thanks for the feedback. If there is only .5" difference between the 17" and 20" tires then the 20" tires must be lower profile tires than the 17" ones. That would be good since I have had the best luck with low profile tires. I have had too many lousy regular profile tires in my lifetime.

HKS